Move old SelectionEvent to V7 and create a new selection event supertype

Change-Id: I17496c803f81fdaa98e47cbfcc9bdc91625c134f

5 files changed, 128 insertions, 136 deletions

diff --git a/server/src/main/java/com/vaadin/event/SelectionEvent.java b/server/src/main/java/com/vaadin/event/SelectionEvent.java
deleted file mode 100644
index b5a4d587e6..0000000000
--- a/server/src/main/java/com/vaadin/event/SelectionEvent.java
+++ /dev/null
@@ -1,132 +0,0 @@
-/*
- * Copyright 2000-2016 Vaadin Ltd.
- *
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not
- * use this file except in compliance with the License. You may obtain a copy of
- * the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations under
- * the License.
- */
-package com.vaadin.event;
-
-import java.io.Serializable;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.EventObject;
-import java.util.LinkedHashSet;
-import java.util.Set;
-
-/**
- * An event that specifies what in a selection has changed, and where the
- * selection took place.
- *
- * @since 7.4
- * @author Vaadin Ltd
- */
-public class SelectionEvent extends EventObject {
-
-    private LinkedHashSet<Object> oldSelection;
-    private LinkedHashSet<Object> newSelection;
-
-    public SelectionEvent(Object source, Collection<Object> oldSelection,
-            Collection<Object> newSelection) {
-        super(source);
-        this.oldSelection = new LinkedHashSet<>(oldSelection);
-        this.newSelection = new LinkedHashSet<>(newSelection);
-    }
-
-    /**
-     * A {@link Collection} of all the itemIds that became selected.
-     * <p>
-     * <em>Note:</em> this excludes all itemIds that might have been previously
-     * selected.
-     *
-     * @return a Collection of the itemIds that became selected
-     */
-    public Set<Object> getAdded() {
-        return setDifference(newSelection, oldSelection);
-    }
-
-    /**
-     * A {@link Collection} of all the itemIds that became deselected.
-     * <p>
-     * <em>Note:</em> this excludes all itemIds that might have been previously
-     * deselected.
-     *
-     * @return a Collection of the itemIds that became deselected
-     */
-    public Set<Object> getRemoved() {
-        return setDifference(oldSelection, newSelection);
-    }
-
-    /**
-     * Slightly optimized set difference that can return the original set or a
-     * modified one.
-     *
-     * @param set1
-     *            original set
-     * @param set2
-     *            the set to subtract
-     * @return the difference set
-     */
-    private static <T> Set<T> setDifference(Set<T> set1, Set<T> set2) {
-        if (set2.isEmpty()) {
-            return set1;
-        } else {
-            LinkedHashSet<T> set = new LinkedHashSet<>(set1);
-            set.removeAll(set2);
-            return set;
-        }
-    }
-
-    /**
-     * A {@link Collection} of all the itemIds that are currently selected.
-     *
-     * @return a Collection of the itemIds that are currently selected
-     */
-    public Set<Object> getSelected() {
-        return Collections.unmodifiableSet(newSelection);
-    }
-
-    /**
-     * The listener interface for receiving {@link SelectionEvent
-     * SelectionEvents}.
-     */
-    public interface SelectionListener extends Serializable {
-        /**
-         * Notifies the listener that the selection state has changed.
-         *
-         * @param event
-         *            the selection change event
-         */
-        void select(SelectionEvent event);
-    }
-
-    /**
-     * The interface for adding and removing listeners for {@link SelectionEvent
-     * SelectionEvents}.
-     */
-    public interface SelectionNotifier extends Serializable {
-        /**
-         * Registers a new selection listener
-         *
-         * @param listener
-         *            the listener to register
-         */
-        void addSelectionListener(SelectionListener listener);
-
-        /**
-         * Removes a previously registered selection change listener
-         *
-         * @param listener
-         *            the listener to remove
-         */
-        void removeSelectionListener(SelectionListener listener);
-    }
-}
diff --git a/server/src/main/java/com/vaadin/event/selection/MultiSelectionEvent.java b/server/src/main/java/com/vaadin/event/selection/MultiSelectionEvent.java
index 1de911f353..c79b405523 100644
--- a/server/src/main/java/com/vaadin/event/selection/MultiSelectionEvent.java
+++ b/server/src/main/java/com/vaadin/event/selection/MultiSelectionEvent.java
@@ -16,6 +16,7 @@
 package com.vaadin.event.selection;
 
 import java.util.Collections;
+import java.util.Optional;
 import java.util.Set;
 
 import com.vaadin.data.HasValue.ValueChange;
@@ -33,7 +34,8 @@ import com.vaadin.ui.AbstractListing;
  * @param <T>
  *            the data type of the selection model
  */
-public class MultiSelectionEvent<T> extends ValueChange<Set<T>> {
+public class MultiSelectionEvent<T> extends ValueChange<Set<T>>
+        implements SelectionEvent<T> {
 
     private final Set<T> oldSelection;
 
@@ -75,4 +77,9 @@ public class MultiSelectionEvent<T> extends ValueChange<Set<T>> {
     public Set<T> getOldSelection() {
         return Collections.unmodifiableSet(oldSelection);
     }
+
+    @Override
+    public Optional<T> getFirstSelected() {
+        return getValue().stream().findFirst();
+    }
 }
diff --git a/server/src/main/java/com/vaadin/event/selection/SelectionEvent.java b/server/src/main/java/com/vaadin/event/selection/SelectionEvent.java
new file mode 100644
index 0000000000..28b3fd4461
--- /dev/null
+++ b/server/src/main/java/com/vaadin/event/selection/SelectionEvent.java
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.event.selection;
+
+import java.io.Serializable;
+import java.util.Optional;
+
+/**
+ * A selection event that unifies the way to access to selection event for multi
+ * selection and single selection components (in case when only one selected
+ * item is required).
+ *
+ * @since 8.0
+ * @author Vaadin Ltd
+ * @param <T>
+ *            the data type of the selection model
+ */
+public interface SelectionEvent<T> extends Serializable {
+
+    /**
+     * Get first selected data item.
+     * <p>
+     * This is the same as {@link SingleSelectionChange#getSelectedItem()} in
+     * case of single selection and the first selected item from
+     * {@link MultiSelectionEvent#getNewSelection()} in case of multi selection.
+     * 
+     * @return the first selected item.
+     */
+    Optional<T> getFirstSelected();
+}
diff --git a/server/src/main/java/com/vaadin/event/selection/SingleSelectionChange.java b/server/src/main/java/com/vaadin/event/selection/SingleSelectionChange.java
index fe120c1692..3f4323b9ac 100644
--- a/server/src/main/java/com/vaadin/event/selection/SingleSelectionChange.java
+++ b/server/src/main/java/com/vaadin/event/selection/SingleSelectionChange.java
@@ -29,7 +29,8 @@ import com.vaadin.ui.AbstractListing;
  *            the type of the selected item
  * @since 8.0
  */
-public class SingleSelectionChange<T> extends ValueChange<T> {
+public class SingleSelectionChange<T> extends ValueChange<T>
+        implements SelectionEvent<T> {
 
     /**
      * Creates a new selection change event.
@@ -42,8 +43,8 @@ public class SingleSelectionChange<T> extends ValueChange<T> {
      *            {@code true} if this event originates from the client,
      *            {@code false} otherwise.
      */
-    public SingleSelectionChange(AbstractListing<T, ?> source,
-            T selectedItem, boolean userOriginated) {
+    public SingleSelectionChange(AbstractListing<T, ?> source, T selectedItem,
+            boolean userOriginated) {
         super(source, selectedItem, userOriginated);
     }
 
@@ -64,4 +65,9 @@ public class SingleSelectionChange<T> extends ValueChange<T> {
     public AbstractListing<T, ?> getSource() {
         return (AbstractListing<T, ?>) super.getSource();
     }
+
+    @Override
+    public Optional<T> getFirstSelected() {
+        return getSelectedItem();
+    }
 }
diff --git a/server/src/test/java/com/vaadin/event/selection/SelectionEventTest.java b/server/src/test/java/com/vaadin/event/selection/SelectionEventTest.java
new file mode 100644
index 0000000000..8ae15f5ad2
--- /dev/null
+++ b/server/src/test/java/com/vaadin/event/selection/SelectionEventTest.java
@@ -0,0 +1,68 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.event.selection;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.Optional;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.mockito.Mockito;
+
+/**
+ * @author Vaadin Ltd
+ *
+ */
+public class SelectionEventTest {
+
+    @SuppressWarnings({ "unchecked", "rawtypes" })
+    @Test
+    public void getFirstSelected_mutliSelectEvent() {
+        MultiSelectionEvent<?> event = Mockito.mock(MultiSelectionEvent.class);
+        Mockito.doCallRealMethod().when(event).getFirstSelected();
+
+        Mockito.when(event.getValue())
+                .thenReturn(new LinkedHashSet(Arrays.asList("foo", "bar")));
+
+        Optional<?> selected = event.getFirstSelected();
+
+        Mockito.verify(event).getValue();
+        Assert.assertEquals("foo", selected.get());
+
+        Mockito.when(event.getValue()).thenReturn(Collections.emptySet());
+        Assert.assertFalse(event.getFirstSelected().isPresent());
+    }
+
+    @SuppressWarnings({ "unchecked", "rawtypes" })
+    @Test
+    public void getFirstSelected_singleSelectEvent() {
+        SingleSelectionChange event = Mockito.mock(SingleSelectionChange.class);
+        Mockito.doCallRealMethod().when(event).getFirstSelected();
+
+        Mockito.when(event.getSelectedItem()).thenReturn(Optional.of("foo"));
+
+        Optional<?> selected = event.getSelectedItem();
+
+        Mockito.verify(event).getSelectedItem();
+        Assert.assertEquals("foo", selected.get());
+
+        Mockito.when(event.getSelectedItem()).thenReturn(Optional.empty());
+        Assert.assertFalse(event.getFirstSelected().isPresent());
+    }
+
+}